Highest Total Petroleum Hydrocarbon Research Articles

Effects of Anthropogenic Activities on Sardinella maderensis (Lowe, 1838) Fisheries in Coastal Communities of Ibeju-Lekki, Lagos, Nigeria

Small-scale fisheries are significant sources of nutrition and livelihood globally. However, increasing anthropogenic activities in coastal areas of developing countries have threatened the sustainability of artisanal fisheries and species. Fisheries of Sardinella maderensis, towards the global stock of which Nigeria contributes 9% and which is a significant livelihood source in the coastal communities of Ibeju-Lekki, Lagos, faces sustainability threats. This research investigated the effects of anthropogenic activities on S. maderensis fisheries in the coastal areas of Ibeju-Lekki, Lagos, Nigeria. The study adopted a mixed-method approach involving qualitative and quantitative research methods. These included species identification, water quality analysis, land-use change analysis, field surveys, focus group discussions, and interviews. Genetic analysis of the fish samples from the study area revealed that the species had a mean of 98% similarity to S. maderensis. While major urban and industrial land use has increased by 175% in the last four decades, the catch per unit effort (CPUE) of S. maderensis declined monthly to 0.0072 kg/H between 2003 and 2019. Linear regression indicated that anthropogenic variables explained approximately 39.58% of the variation in the CPUE (p < 0.001, R2 = 0.40). Water samples showed that heavy metal levels were above international limits, with high total petroleum hydrocarbon (TPH) pollution in all stations (27.56 mg/L–3985.40 mg/L). Physiochemical analysis of water samples indicated TDS levels higher than the acceptable limits (mean = 24,971.1 mg/L) and inadequate chlorophyll-a levels (mean = 0.01 µg/L). Hence, urgent strategies are required to mitigate anthropogenic threats through inclusive coastal management policies supporting resilient artisanal fisheries.

Insights on dielectric barrier discharge plasma treatment of oil drilling cuttings

Oil drilling cuttings produced during oil exploration and extraction contain a high percentage of crude oil, ranging from 5% to 20% weight ratio (w/w) on a dry basis, and must be managed and treated properly before their release to the environment. In this study, non-thermal plasma (NTP) was investigated as an advanced oxidation process for the efficient, sustainable and cost-effective treatment of oil drilling cuttings. To this end, a plane-to-grid dielectric barrier discharge (DBD) reactor operating at atmospheric pressure was tested under different plasma conditions. The effect of treatment time, DBD power and air flow rate on the total organic carbon (TOC) removal efficiency was assessed and the energy efficiency of the process was determined. Within 10 min of plasma treatment, a very high TOC and total petroleum hydrocarbons (TPH) removal (∼90% and ∼99%, respectively) was achieved, while polycyclic aromatic hydrocarbons (PAHs) were degraded by ∼50% within 2 min of treatment. Depending on the experimental conditions, the energy efficiency of the process varied from 5 to 35 mg/kJ. From GC-MS analysis, several byproducts of the oxidation of oil drilling cuttings were identified, while the analysis of exhaust gases revealed that ∼85.1% of the removed organics from oil drilling cuttings was transformed to CO2 and CO. This study provides critical information on the effectiveness of the NTP process for the treatment of heavily contaminated solid wastes and can be considered as the critical step for its application for the treatment of solid wastes from the oil industry.

Water conditions and arbuscular mycorrhizal symbiosis affect the phytoremediation of petroleum-contaminated soil by Phragmites australis

Phytoremediation of petroleum-contaminated soils using the synergistic functions of plants and rhizosphere microorganisms is a promising technology. However, successfully applying this approach presents challenges under certain conditions (submerged environments). This study analyzed the potential role of Phragmites australis in symbiosis with arbuscular mycorrhizal (AM) fungi during petroleum remediation at two water levels. AM inoculation promoted P. australis aboveground growth under non-flooded conditions, whereas flooding significantly increased P. australis biomass. The highest total petroleum hydrocarbon (TPH) degradation efficiency was observed in non-flooded soils, whereas submergence severely inhibited TPHs dissipation. Plants with AM inoculation treatments substantially enhanced the removal of TPHs under flooded conditions. TPH removal was positively correlated with dehydrogenase activity but negatively correlated with easily extracted glomalin-related soil proteins. Moreover, different petroleum-hydrocarbon-decaying candidates contributed to TPH removal in these two cultured soils. These findings provide valuable information for the remediation of future TPH-contaminated soils, especially applied in intermittently submerged environments.

Groundwater-level fluctuation effects on petroleum hydrocarbons in vadose zones and their potential risks: Laboratory studies

Despite the role of the vadose zone protecting groundwater from contamination, the non-stationarity in this zone makes it difficult to predict the behavior of petroleum hydrocarbons (PH) therein. In laboratory soil columns with sandy and sandy loam soils, we simulated a vadose zone subjected to repeated groundwater-level fluctuation (GLF) to evaluate the behavior of PH under hydrodynamic conditions. The GLF vertically redistributed the PH, the extent of which was pronounced in the sandy soil with a high initial concentration due to the enhanced transport of the immiscible PH through the larger pores. The frequency of GLF did not show a substantial effect on the extent of PH redistribution but largely affected their attenuation. The greater GLF hindered PH volatilization by maintaining a high degree of water saturation, while the subsequent development of a local anaerobic regime inhibited biodegradation, which was more apparent in the sandy loam. Finally, a specific potential risk index was introduced to quantitatively compare the potential risk of PH contamination in different vadose zones exposed to GLF. Overall, the sandy soil contaminated with the higher total PH (TPH) concentration showed markedly higher potential risk indices (i.e., 18.4–29.0%), while the ones comprised of the sandy loam showed 0.6–4.9%, which increased under the greater number of GLF cycles.

Potential natural attenuation of petroleum hydrocarbons in fuel contaminated soils: Focusing on anaerobic fuel biodegradation involving microbial Fe(III) reduction

Liquid fossil fuels, collectively known as total petroleum hydrocarbons (TPHs), are highly toxic and frequently leak into subsurface environments due to anthropogenic activities. As an in-situ biological remedial option for TPH contamination, aerobic TPH biodegradation is limited due to oxygen's low solubility in water, and because it is consumed quickly by aerobic bacteria. Thus, we investigated the potential of anaerobic TPH degradation by indigenous fermenting bacteria and Fe(III)-reducing bacteria. Twenty 6–10 m soil cores were collected from a closed military base subject to ongoing TPH contamination since the 1980s. Physicochemical and microbial properties were determined at 0.5-m intervals in each core. To assess the relationship between TPH degradation and microbial Fe(III) reduction, soil samples were grouped into high-TPH (>500 mg kg−1) and high-Fe(II) (>450 mg kg−1), high-TPH and low-Fe(II), low-TPH and high-Fe(II), and low-TPH and low-Fe(II) groups. Alpha diversity was significantly lower in high-TPH groups than in low-TPH groups, suggesting that high TPH concentrations exerted a strong selective pressure on bacterial communities. In the high-TPH and low-Fe(II) group, fermenting bacteria, including Microgenomatia and Chlamydiae, were more abundant, suggesting that TPH biodegradation occurred via fermentation. In the high-TPH and high-Fe(II) group, Fe(III)-reducing bacteria, including Geobacter and Zoogloea, were more abundant, suggesting that microbial Fe(III) reduction enhances TPH biodegradation. In contrast, the fermenting and/or Fe(III)-reducing bacteria were not statistically abundant in the low-TPH groups.

Pollution of the Niger Delta with total petroleum hydrocarbons, heavy metals and nutrients in relation to seasonal dynamics

The African Niger Delta is among the world’s most important wetlands in which the ecological effects of intensive oil exploitation and global change are not well documented. We characterized the seasonal dynamics and pollution with total-petroleum-hydrocarbons (TPHs), heavy-metals (HMs) and nutrient-loads in relation to climate-driven variables. High TPH concentrations up to 889 mg/L and HMs up to 13.119 mg/L were found in water samples, with pronounced spatio-temporal variation throughout the year. HM pollution index and contamination factor indicate serious ecological and human health hazards, especially for Cd, Cu, Hg, and Ni. Significant differences in TPHs/HMs were observed between sites and seasons, with correlations between TPHs-HMs, and climate-variables and TPHs-HMs. Nutrient levels, turbidity, salinity, temperature, and SO42- were high and interlinked with the variability of TPHs/HMs being greatest during wet season. These findings suggest an urgent need for improved pollution control in the Niger Delta taking into account the observed spatio-temporal variation and the exacerbation of effects in light of climate change. Given the high levels of contamination, further assessments of exposure effects and bioaccumulation in biota should include future climate change scenarios and effects on humans who intensively depend on the system for drinking water, food supply and livelihood.

Germination Capacity of Helianthus annuus Less Seeds on Soil Media Contaminated by Waste

Used oil waste is often dumped on the ground around the workshop, causing soil pollution which can reduce the function of the soil. The most difficult contaminants in used oil waste to decompose are hydrocarbon compounds, which are highly toxic, polycyclic aromatic hydrocarbons (PAHs). The concentration of oil hydrocarbon contaminants in a sample is determined by measuring the total petroleum hydrocarbon (TPH) concentration. This study was conducted to determine the germination ability of Helianthus anuus, Less seeds on soil media contaminated with waste oil at different concentrations of Total Petroleum Hydrocarbon (TPH). The results showed that the concentration of TPH in the media could inhibit the speed of seed germination. Treatment with low concentration of TPH 2.7% in the media increased % germination, shoot and root length and sprout biomass compared to the medium/intermediate (8.00%) and high (12.26%) TPH treatments and controls. However, there was no significant difference between all treatments regarding germination time and shoot length, although in the low TPH treatment (2.70%) there was a tendency for germination time to be faster than the other treatments, as well as to shoot length which was longer than the other treatments. The higher TPH concentration in the media can inhibit germination time, germination percentage, shoot and root length and biomass. Morphological observations of the growth of sprouts showed an inhibition of root hair formation along with the high TPH content in the media, but all treatments did not affect the growth of the shoots.

Response of soil microbial communities to petroleum hydrocarbons at a multi-contaminated industrial site in Lanzhou, China

Total petroleum hydrocarbon (TPH) contamination poses threats to ecological systems and human health. Many studies have reported its negative impacts on soil microbes, but limited information is known about microbial change and response to multiple TPH contamination events. In this study, we investigated TPH contamination level, microbial community structure and functional genes at a multi-contaminated industrial site in Lanzhou, where a benzene spill accident caused the drinking water crisis in 2014. TPHs distribution in soils and groundwater indicated multiple TPH contamination events in history, and identified the spill location where high TPH level (6549 mg kg−1) and high ratio of low-molecular-weight TPHs (>80%) were observed. In contrast, TPH level was moderate (349 mg kg−1) and the proportion of low-molecular-weight TPHs was 44% in soils with a long TPH contamination history. After the spill accident, soil bacterial communities became significant diverse (p = 0.047), but the dominant microbes remained the same as Pseudomonadaceae and Comamonadaceae. The abundance of hydrocarbon-degradation related genes increased by 10–1000 folds at the site where the spill accident occurred in multi-contaminated areas and was significantly related to 2-ring PAHs. Such changes of microbial community and hydrocarbon-degradation related genes together indicated the resilience of soil indigenous microbes toward multiple contamination events. Our results proved the significant change of bacterial community and huge shift of hydrocarbon-degradation related genes after the spill accident (multiple contamination events), and provided a deep insight into microbial response at industrial sites with a long period of contamination history.

BIOTREATABILITY OF PETROLEUM REFINERY SLUDGE USING LAND - FARMING AND ANAEROBIC DEGRADATION TECHNIQUES

One of the major problems faced by oil industries and the environment, is the safe disposal of oily sludge generated during the processing of crude oil. Biotreatability of petroleum refinery sludge using bioremediation and anaerobic degradation techniques was studied. Analysis of the Nigerian Petroleum Refinery sludge used for this research indicated that the sludge is slightly acid with high total petroleum hydrocarbon (TPH) content of 340,000mg/kg and polyaromatic hydrocarbon (PAH) content of 0.075mg/kg. The heterotrophic bacterial and fungal counts were 5.86 x 105 and 4.72 x 105cfu/g respectively while the hydrocarbon degrading bacterial and fungal count were 2.85 x 102 and 2.75 x 102 cfu/g respectively. Results from biotreatability studies revealed that the sludge contamination at lower concentration 10,000 (1%) mg/kg, recorded high percentage degradation than the treatment with higher sludge concentration, 50,000 (5%) mg/kg. Biostimulation treatments enhanced the sludge degradation better than the natural attenuated treatment. Volume of biogas produced in the anaerobic microcosm was highest in the treatment with compost in both 1% (10.73 l/kg) and 5% (9.27 l/kg) sludge treatments. Though the NPK treated soil enhanced the biodegradation of sludge most, degradation started declining by the 9th week while that of compost continued to rise steadily till the 12th week. Anaerobic process was quite slow and did not degrade the sludge as much as the aerobic land – farming method.

English

The study investigated microbial population dynamics in soils of Greater Port Harcourt Area, Nigeria. The study involved the quantification of petroleum pollutants and the enumeration and characterization of culturable fungi and bacteria. Gas Chromatograph FID method was used to quantify total petroleum hydrocarbons (TPH) in the soil while morphological and biochemical tests were used to characterize the microorganisms. The highest TPH was 9,759.37±883.36 ppm which exceeded the Department of Petroleum Resources’ (DPRs’) intervention value of 5,000 ppm. The percentage of hydrocarbon utilizing fungi (% HUF) ranged between 1.93±0.57 and 66.55±5.60 which were observed in sites A1 (Aluu) and CA (Agricultural control), respectively. The percentage of hydrocarbon utilizing bacteria (% HUB) ranged between 0.12±0.01 and 7.89±1.25 which was observed in sites A3 (Emuoha) and CU (Urban control), respectively. The most prevalent bacterial species includes Bacillus subtilis, Micrococcus lylae, Staphylococcus aureus, Bacillus cereus and Alcaligen faecalis. The most prevalent HUB isolate was Bacillus subtilis. The most prevalent fungal isolates were Aspergillus niger, Aspergillus flavus and Candida torulopsis. A. niger was the most prevalent among the HUF isolates which was identified in 12 sites. It was concluded that the study sites harboured TPH degrading microorganisms that are appropriate for bioremediation of TPH polluted sites.   Key words: Total petroleum hydrocarbons, soil pollution, biodiversity, fungi, bacteria.

Phytoremediation of soils contaminated with crude and weathered oil using two rice varieties (Oryza sativa L.)

Objective: To evaluate the potential for soil phytoremediation with new and weathered hydrocarbons with two rice varieties (Oryza sativa L.). Materials and Methods: The assessed treatments were 150 mg kg-1 (control soil), 30,000; 60,000 and 90,000 mg kg-1 of new oil and 79,457 mg kg-1 of weathered oil 1 and 42,000 of mg kg-1 of weathered oil 2; they were established in a completely randomized design with 6 x 3 factorial, with four repetitions each. The evaluated variables were populations of total bacteria (colony forming units CFU per grams of dry soil), free-living nitrogen-fixing bacteria (CFU), total fungi (CFU), and total dry biomass (g). Total bacteria and fungi were quantified at the beginning of the experiment at 90 and 145 days. Results: The highest total petroleum hydrocarbons (HTP) degradation was 73 and 72 % in the 79,457 and 42,000 mg kg-1 concentrations of weathered HTP 1 and 2, in the rhizosphere of rice silver line 21. The total dry biomass reported significant differences (p ≤ 0.05), evidencing a lower effect in the 60,000 mg kg-1 concentration in new oil, which caused a 33 % reduction compared to the control. Results/Conclusions: The rice variety line 21 has a greater potential to phytoremediate soils contaminated with crude and weathered oil in field conditions in tropical areas.

Valorization of petroleum refinery oil sludges via anaerobic co-digestion with food waste and swine manure

Valorization of oil sludge has been gaining attention to improve the sustainability of the petroleum industry. This study aimed to assess the possibility of anaerobic co-digestion of oil scum and secondary sludge with food waste (or swine manure). Oil scum and secondary sludge were obtained from a wastewater treatment plant (WWTP) of a petrochemical plant. Physicochemical properties, hazardous materials, and microbial community were characterized and biochemical methane potential was performed by a simplex-lattice mixture design. More than 87% (wet wt.) of the oil scum consisted of total petroleum hydrocarbons (TPHs) (21,762 mg/L) that are difficult to be degraded by anaerobes. The secondary sludge showed low TPHs (5 mg/L) and a bacterial community similar to that of municipal WWTPs. The heavy metal (Cu, As, Cr, Ni, Mn, Zn, and V) concentrations in the oil scum and secondary sludge were similar (20–600 mg/L). The maximum methane potentials of the oil sludge and secondary sludges were 20 ± 2 and 56 ± 3 mL CH4/g-volatile solid, respectively. The co-digestion with food waste or swine manure led to a synergy effect on methane production of the co-digestion substrate (10–40% increase compared to the calculated value; v/v) by balancing the C/N ratio. Due to the high TPH contents, oil scum is not appropriate for co-digestion. The co-digestion of secondary sludge with food waste and/or swine manure is recommended. It is necessary to consider whether the concentration of heavy metals is at a level that inhibits the anaerobic co-digestion depending on the operating conditions such as mixing ratios and solid contents.

Physicochemical Indices of Phyto Remediated Hydrocarbon Polluted Soil and the Effect of Bio-nutrient Amendment

Aim: To assess the Physicochemical indices of Phytoremediated Crude Oil polluted amended soil using grass plant Cyperus esculentus (Cyp) and Phyllanthus amarus (Phy).
 Study Design: The study employs experimental design, statistical analysis of the data and interpretation.
 Place and Duration of Study: Rivers State University demonstration farmland in Nkpolu- Oroworukwo, Mile 3 Diobu area of Port Harcourt, was used for this study. The piece of land is situated at Longitude 4°48’18.50” N and Latitude 6ᵒ58’39.12” E measuring 5.4864 m x 5.1816 m with a total area of 28.4283 square meter. Phytoremediation process monitoring lasted for 240 days; analyses were carried out monthly at 30 days’ interval.
 Methodology: The study was carried out on Crude Oil Polluted soil (PS) amended with bio-nutrient supplements (Spent Mushroom Substrate (SMS) and selected fungi (Aspergillus niger(AN) andMucor racemosus (MR)) used to stimulate and augment the indigenous microbial population present in a crude oil polluted soil thereby enhancing hydrocarbon reduction in pari per sue with phytoremediation (uptake of Crude oil by test plants) over a period of 240 days. Ten (10) experimental plots (two Control (Unpolluted and polluted soil without amendment) and eight polluted amended/treated plots) employing Randomized Block Design (each having dimensions: 100 x 50 x 30 cm LxBxH); formed and mapped out on agricultural soil and left fallow for 6 days before contamination on the seventh day; after which it was allowed for 21 days for proper contamination and exposure to natural environmental factors (to mimic soil crude oil spill site); thereafter nutrients/organics (biostimulating agents) and bioaugmenting organisms were applied. Baseline studies were carried out on soil profile before and after contamination, major parameters monitored and assayed were Total Petroleum Hydrocarbon (TPH) uptake by plant roots and stem, Polycyclic Aromatic Hydrocarbons (PAHs) and TPH reduction in soil. Other physicochemical properties analyzed in the soil from different plots were pH, Electrical Conductivity, Moisture Content, Total Nitrogen, Available Phosphorus, Potassium, Total Organic Carbon, Plant Height, Iron, Lead and Zinc at regular intervals; days 1, 60, 90, 120, 150, 180, 210 & 240. The rate of phytoremediation was estimated from percentage (%) uptake of Total petroleum hydrocarbon (TPH) in plant roots and stem from day 1 -240; while percentage (%) reduction of TPH and PAHs in soil was estimated from day 1 to the residual at day 240.
 Results: The test plants decreased significant amount of crude oil as revealed in TPH uptake in their roots and Stem. Mean amount and percentage Total Petroleum Hydrocarbon (TPH) uptake by Cyperus esculentus roots and stem were; 152.33±50.34mg/kg, 12.57±4.16% and 201.13±8.80mg/kg, 13.27±0.58% respectively; while that of Phyllanthus amarusroots and stem were 141.50±35.62mg/kg, 11.68±2.94% and 174.44±19.98mg/kg, 11.51±1.32% respectively; revealing higher Uptake of TPH in plant stem than roots. From the initial TPH contamination value of 5503.00mg/kg, it was observed that plots planted with Cyperus esculentus (TPH 5492.75±76.36mg/kg) showed higher reduction of TPH from soil than those planted with Phyllanthus amarus(TPH 5449.72±18.27mg/kg); while PAHs degradation/reduction showed a reverse trend with plots planted with Phyllanthus amarus (PAHs 28.72±2.74mg/kg; 60.46±5.77%) higher than plots planted with Cyperus esculentus
 s (PAHs 25.77±2.12mg/kg, 54.24±4.47%).
 Conclusion: Plots planted with Cyperus esculentus showed higher reduction of TPH from soil than those planted with Phyllanthus amarus while PAHs degradation/reduction in plots planted with Phyllanthus amarus was higher than plots planted with Cyperus esculentus. TPH uptake was higher in plant stems than roots; more so, plots amended with nutrient supplements showed significant higher percentage reduction in hydrocarbon in the polluted soil than unamended polluted soil. It is therefore recommended that Cyperus esculentus is a suitable plant species for phytoremediation of crude oil contaminated soil with high TPH value while Phyllanthus amarusis the best option in phytoremediation of polluted soil with high PAHs value, both in combination with bio-nutrient supplement.

Enhanced pilot bioremediation of oily sludge from petroleum refinery disposal under hot-summer Mediterranean climate

Large pilot scale bioremediation approaches were implemented for the treatments of oily sludge (OS) characterised by alkaline pH (pH > 9), high concentration of metals (3% dry weight) and high total petroleum hydrocarbons content (TPH) rangingbetween 22,000 and 67,300 mg kg −1 from a Tunisian petroleum refinery. The treatments included bioaugmentation and biostimulation approaches with autochthonous isolated bacterial strains and consortia. Chemical, microbial, and ecotoxicological analyses were performed over a period of 180 days incubation. The bioremediation treatments favoured the development of Proteobacteria , Firmicutes and Bacteroidetes following an ecological succession of specialist bacterial groups, first associated to hydrocarbon degradation (e.g. Marinobacter and Alcanivorax ) that resulted in a greater extent of TPH-degradation (up to 80%), and the selection of metal resistant bacteria including Hyphomonas , Phaeobacter , and Desulfuromusa . The best performances were obtained when bioaugmentation and biostimulation were combined. Over 90% of the TPH initial concentration was degraded over 180 days, which was accompanied with a 3-fold reduction of ecotoxicity. Our study demonstrates the efficacy of large pilot scale bioremediation of highly contaminated oily sludge, providing the evidence that the management of autochthonous microbial communities is of paramount importance for the success of the bioremediation process. • Effective oil sludge bioremediation by managing bacterial community. • Optimal treatment combining bioaugmentation and biostimulation. • Bacterial community plasticity evidenced through ecological succession.

Electro-Kinetic Degradation of Diesel Originated from a Costal Crude Oil Terminal

: The present study evaluated the effect of the integration of electro-kinetic (EK) oxidation with sonication degradation of diesel in a hydrocarbon contaminated wastewater. The effect of operational parameters including initial pH (3 - 9), sonication (100 - 300 W), voltage (0.5 - 3 V/cm), and reaction time (60 - 150 min) were studied consecutively. The highest total petroleum hydrocarbon (TPH) destruction rate of 40% was achieved at pH 5. Also, increasing the sonication intensity up to 300 W improved the removal rate to 70%. The pseudo-first-order kinetic model was selected due to higher correlation coefficient. Considering the obtained integration of EK oxidation with sonication is a viable and efficient technology for treatment of diesel contaminated wastewaters.

Enhanced degradation of petroleum hydrocarbons by immobilizing multiple bacteria on wheat bran biochar and its effect on greenhouse gas emission in saline-alkali soil

In this study, an immobilization method for forming and keeping dominant petroleum degradation bacteria was successfully developed by immobilizing Pseudomonas, Acinetobacter, and Sphingobacterium genus bacteria on wheat bran biochar pyrolyzed at 300, 500, and 700 °C. The removal efficiency indicated that the highest TPHs (total petroleum hydrocarbons) removal rate of BC500–4 B (biochar pyrolyzed at 500 °C with four kinds of petroleum bacteria) was 58.31%, which was higher than that of BC500 (36.91%) and 4 B (43.98%) used alone. The soil properties revealed that the application of biochar increased the content of organic matter, available phosphorus, and available potassium, but decreased pH and ammonium nitrogen content in soil. Bacterial community analysis suggested that the formation of dominant degrading community represented by Acinetobacter played key roles in TPHs removal. The removal rate of alkanes was similar to that of TPHs. Besides, biochar and immobilized material can also mediate greenhouse gas emission while removing petroleum, biochar used alone and immobilized all could improve CO2 emission, but decrease N2O emission and had no significant impact on CH4 emission. Furthermore, it was the first time to found the addition of Acinetobacter genus bacteria can accelerate the process of forming a dominant degrading community in wheat bran biochar consortium. This study focused on controlling greenhouse gas emission which provides a wider application of combining biochar and bacteria in petroleum soil remediation.

Growth Optimisation and Kinetic Profiling of Diesel Biodegradation by a Cold-Adapted Microbial Consortium Isolated from Trinity Peninsula, Antarctica.

Simple SummaryDiesel fuel is very crucial for anthropogenic activities in Antarctica and the surges in annual demand mean higher likelihood of spillages from improper handling during transportation, storage and disposal processes. The impacts can be very extensive or well-contained depending on the scale of the spills as well as the terrain involved. Nevertheless, the freezing temperature and prolonged solar irradiance in the south pole greatly hampered the natural attenuation and photovolatilisation of petrogenic hydrocarbons, contributing to their persistency. The most susceptible groups are the soil microorganisms, mosses, seabirds and pinnipeds as they are easily found near the shore where hydrocarbons spillage is very common. Microbial bioremediation is a well-established approach in restoring many hydrocarbons-polluted areas, thus the current study focused on the optimisation and application of locally isolated microbial consortium to simulate the in situ diesel clean-up process in aqueous medium. This study highlights the ability of the selected consortium to degrade diesel almost completely at moderately low temperature, suggesting its potential application in Antarctic settings.Pollution associated with petrogenic hydrocarbons is increasing in Antarctica due to a combination of increasing human activity and the continent’s unforgiving environmental conditions. The current study focuses on the ability of a cold-adapted crude microbial consortium (BS24), isolated from soil on the north-west Antarctic Peninsula, to metabolise diesel fuel as the sole carbon source in a shake-flask setting. Factors expected to influence the efficiency of diesel biodegradation, namely temperature, initial diesel concentration, nitrogen source type and concentration, salinity and pH were studied. Consortium BS24 displayed optimal cell growth and diesel degradation activity at 1.0% NaCl, pH 7.5, 0.5 g/L NH4Cl and 2.0% v/v initial diesel concentration during one-factor-at-a-time (OFAT) analyses. The consortium was psychrotolerant based on the optimum growth temperature of 10‒15 °C. In conventionally optimised media, the highest total petroleum hydrocarbons (TPH) mineralisation was 85% over a 7-day incubation. Further optimisation of conditions predicted through statistical response-surface methodology (RSM) (1.0% NaCl, pH 7.25, 0.75 g/L NH4Cl, 12.5 °C and 1.75% v/v initial diesel concentration) boosted mineralisation to 95% over a 7-day incubation. A Tessier secondary model best described the growth pattern of BS24 in diesel-enriched medium, with maximum specific growth rate, μmax, substrate inhibition constant, Ki and half saturation constant, Ks, being 0.9996 h−1, 1.356% v/v and 1.238% v/v, respectively. The data obtained suggest the potential of microbial consortia such as BS24 in bioremediation applications in low-temperature diesel-polluted soils.

Bio-electrocatalytic remediation of hydrocarbons contaminated soil with integrated natural attenuation and chemical oxidant

The present study aimed to assess the possibility of integrating natural attenuation (NA) and chemical oxidation (O) with the bio-electrocatalytic remediation (BET) process to remediate petroleum hydrocarbons contaminated soil. Six different reactors were operated, wherein in the first reactor was a NA system, and the second condition to the NA was supplemented with a chemical oxidant (NAO). These systems were compared with BET systems which were differentiated based on the position and distance between the electrodes. The study was performed by considering NA as a common condition in all the six different reactors viz., NA, NAO, NA + BET with 0.5 cm space amid electrodes (BETH-0.5), NAO + BET with 0.5 cm space amid electrodes (BETOH-0.5), NAO + BET with 1.0 cm space amid electrodes (BETOH-1.0), and NAO + BET with vertical electrodes at 1.0 cm distance (BETOV-1.0). The highest total petroleum hydrocarbons (TPH) degradation efficiency was observed with BETOH-0.5 (67 ± 0.8%) followed by BETOH-1.0 (62 ± 0.6%), BETH-0.5 (60%), BETOV-1.0 (56 ± 0.5%), NAO (46.6%), and NA (27.7%). In NA, the indigenous microorganisms remediate the organic contaminants. In the NAO system, KMnO4 actively breakdown the carbon-carbon double bond functional group. Further, in BETOH-0.5, an anodophilic bacteria enriched around the electrode reported enhanced treatment efficiency along with a maximum of 260 mV (1.65 mA). BET systems integrated with chemical oxidation processes were much more effective in the TPH removal process than an individual process. The BET method adopted here thus provides a good opportunity for bio-electrocatalytic remediation of TPH and resource recovery in the form of bioelectricity.

Bioaugmentation of Native Fungi, an Efficient Strategy for the Bioremediation of an Aged Industrially Polluted Soil With Heavy Hydrocarbons.

The concurrence of structurally complex petroleum-associated contaminants at relatively high concentrations, with diverse climatic conditions and textural soil characteristics, hinders conventional bioremediation processes. Recalcitrant compounds such as high molecular weight polycyclic aromatic hydrocarbons (HMW-PAHs) and heavy alkanes commonly remain after standard soil bioremediation at concentrations above regulatory limits. The present study assessed the potential of native fungal bioaugmentation as a strategy to promote the bioremediation of an aged industrially polluted soil enriched with heavy hydrocarbon fractions. Microcosms assays were performed by means of biostimulation and bioaugmentation, by inoculating a defined consortium of six potentially hydrocarbonoclastic fungi belonging to the genera Penicillium, Ulocladium, Aspergillus, and Fusarium, which were isolated previously from the polluted soil. The biodegradation performance of fungal bioaugmentation was compared with soil biostimulation (water and nutrient addition) and with untreated soil as a control. Fungal bioaugmentation resulted in a higher biodegradation of total petroleum hydrocarbons (TPH) and of HMW-PAHs than with biostimulation. TPH (C14-C35) decreased by a 39.90 ± 1.99% in bioaugmented microcosms vs. a 24.17 ± 1.31% in biostimulated microcosms. As for the effect of fungal bioaugmentation on HMW-PAHs, the 5-ringed benzo(a)fluoranthene and benzo(a)pyrene were reduced by a 36% and 46%, respectively, while the 6-ringed benzoperylene decreased by a 28%, after 120 days of treatment. Biostimulated microcosm exhibited a significantly lower reduction of 5- and 6-ringed PAHs (8% and 5% respectively). Higher TPH and HMW-PAHs biodegradation levels in bioaugmented microcosms were also associated to a significant decrease in acute ecotoxicity (EC50) by Vibrio fischeri bioluminiscence inhibition assays. Molecular profiling and counting of viable hydrocarbon-degrading bacteria from soil microcosms revealed that fungal bioaugmentation promoted the growth of autochthonous active hydrocarbon-degrading bacteria. The implementation of such an approach to enhance hydrocarbon biodegradation should be considered as a novel bioremediation strategy for the treatment of the most recalcitrant and highly genotoxic hydrocarbons in aged industrially polluted soils.

Bioremediation of diesel polluted soils with Eichhornia crassipes (water hyacinth)

Diesel oil contamination is a growing environmental concern in most crude oil processing regions of the world. This study assessed the efficacy of both fresh and powdered Eichhornia crassipes (water hyacinth) as potential biostimulants in the remediation of diesel oil contaminated soils using three test concentrations (50 g, 100 g and 150 g) and a control (0 g). The remediation process was monitored by assaying the total organic carbon (TOC), total petroleum hydrocarbon (TPH), and soil pH before and after amendment with the fresh and powdered E. crassipes for 90 days. The result showed increase in soil pH, TOC, TPH and volatile matter (VM) in comparison with the control due to soil contamination by diesel oil. However, there was a significant reduction (p < 0.05) in soil pH and TOC with the introduction of fresh and powdered E. crassipes at different concentrations. Contaminated soil amended with 100 g of fresh E. crassipes showed the highest TOC loss (59.7%) alongside soil amended with 100 g of powdered E. crassipes (47.36%) while the control showed the least TOC loss (0.91%). Similarly, soil TPH decreased significantly across all concentrations after amendment (p < 0.05). Overall, soil amended with fresh E. crassipes showed higher TPH loss than soil amended with powdered E. crassipes. This study reveals the potentials of using E. crassipes in the remediation of diesel oil contaminated soils. Above all, we demonstrate that fresh E. crassipes is a potentially stronger biostimulant than powdered E. crassipes.